I have a 4 year old fantail goldfish, and recently added a pleco to the tank. The pleco introduced ich to the tank before he unfortunately died. My fantail was shortly pretty covered in trophozoites. I moved the fantail to a QT tank with filtration and an additional airstone to aid in water circulation (trying to keep oxygen levels high as his gills were spotted with ich). I treated with a very slight temperature increase, an increase in aquarium salt, and Rid-Ich (malachite green and formalin). The spots are fewer and fewer, and I know the malachite green is killing the swimmers before they can re-infect. However, one side of my fish now looks incredibly damaged from the emerging of the trophozoites, and I'm worried about other infections taking advantage of the lesions. My questions: 1. Can I treat with an antibacterial in addition to the ich treatment (I have MelaFix) or will more chemicals just stress my fish? 2. I know that there is evidence for the ich cysts remaining dormant in the old tank, and another fish did die in it. What do I do to sterilize my larger tank? I was planning to do a complete dry-out and bleach, but that means starting my bacteria levels from scratch again. 3. Is there anything else I can do for my fantail? He's sitting on the bottom, not swimming or eating. Having the dots off his gills will help, but I am concerned. Thank you!